Refrigeration system

ABSTRACT

In a multiphase refrigeration system based on the Kirk cycle and operating with a refrigerant, expansion pistons and compression pistons are respectively connected to two separate crankshafts mechanically intercoupled with each other for synchronous rotation with a specific phase angle therebetween, and an appropriate number of heat exchangers, regenerators, and cold stations are installed between expansion and compression spaces on which the expansion and compression pistons act.

United States Patent n91 Ishizaki Kohler 62/6 11 3,803,857 [451 Apr. 16, 1974 3,157,025 11/1964 McCrory 62/6 3,274,786 9/1966 Hogan 62/6 3,368,360 2/1968 Saly 62/6 Primary Examiner-William J. Wye Attorney, Agent, or Firm-Stevens, Davis, Mil1er'& Mosher [5 7 ABSTRACT In a multiphase refrigeration system based on the Kirk cycle and operating with a refrigerant, expansion pistons and compression pistons are respectively connected to two separate crankshafts mechanically intercoupled with each other for synchronous rotation with a specific phase angle therebetween, and an appropriate number of heat exchangers, regenerators, and cold stations are installed between expansion and compression spaces on which the expansion and compression pistons act.

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' REFRIGERATION SYSTEM BACKGROUND This invention relates generally to refrigeration and apparatus therefor and more particularly to a new and advanced refrigeration system comprising, essentially, a Kirk cycle refrigerator having compression pistons and expansion pistons respectively connected to and driven by separate crankshafts mechanically intercoupled together for synchronous rotation with a suitable phase angle set therebetween and a compressor operating according to the Joule-Thomson cycle and constructed integrally with the refrigerator.

When theSterling cycle generally known as an internal combustion engine cycle is applied to a refrigerator, the resulting thermodynamic cycle is commonly called a Kirk cycle. 1

In Kirk-cyclerefrigerators known heretofore, the compression piston and the expansion piston in each case have been driven by the same crankshaft. For this reason, these known refrigerators have been accompanied by various difficulties such as complicated construction, poor mechanical balance, and damage to various parts in a short time. Furthermore, since the phase angle between the two kinds of pistons has been so. fixed as to obtain maximum refrigeration output with respect to theobjective temperarure, it has not been possible infthe prior art to attain maximum mechanical and thermal'efficiencies. I i

In additionffor transferring refrigeration output or carrying out liquefaction byrecovering therefrigeration output generated by the above described refrigerator, it has been the common practice to use a compressor and heat exchanger of a construction separate from this refrigerator. v

Accordingly, the apparatus has required two independent units, thereby giving rise to several further difficulties such as large mechanical loss, low thermal efficiency, generation of vibration and noise, complex flowpaths, necessity ofcontinually supplyingthe working gas of the refrigerator at a predetermined pressure from a storage cylinder because of the independent arrangement, and large required floorspace and weight.

SUMMARY Accordingly, an object of this invention is to overcome the above described difficulties in the prior art.

According to this invention in one aspect thereof, briefly summarized, there is provided a refrigeration system, including a main refrigerator operable with a working fluid, in which expansion pistons and compression pistons are respectively connected to separate crankshafts mechanically intercoupled together for synchronous rotation with a specific phase angle therebetween, and an appropriate number of heat exchangers, regenerators, and cold stations are installed between expansion spaces and compression spaces on which the expansion and compression pistons act.

According to this invention in another aspect thereof, there is provided a refrigeration system as set forth above in which the compression spaces and/or expansion spaces are organized to constitute a compressor for compressing a fluid supplied as the working fluid of the refrigerator and as a balancing agent of the pistons and, moreover, supplied as a working fluid for utilizing the cooling output produced by the refrigerator to accomplish successive cooling in heat exchangers additionally provided in plural number and to carry out a process according to the Joule-Thomson cycle thereby to accomplish an operation comprising transfer of the resulting refrigeration output to a remote position and liquefaction of the gaseous working fluid.

According to this invention in still another aspect thereof, there is provided a refrigeration system as set forth above in which a refrigerator is provided in addition to the main refrigerator and operated to carry out pre-cooling based on the Joule-Thomson cycle.

The nature, principle, and further features of this invention will beapparent from the following detailed de scription with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings, in which like parts are designated by like reference numerals and characters.

DRAWINGS In the drawings:

FIG. 1 is a diagrammatic side view, in longitudinal section, indicating the essential organization and principle of an example of a three-phase refrigerator constituting an important part of the refrigeration system according to this invention;

FIGS/2A, 2B, and 2C are graphical representations indicating the operational principle of the refrigerator of the invention; I

FIG. 3 is an end view in the direction'of the axes of the crankshafts, mostly in cross section, illustrating one practical example of embodiment of the invention;

FIG. 4 is a partial sectional view, similar to FIG. 3, showing another example of practice of the invention;

FIG. 5 is a partial sectional view, similar to FIG. 4, showing still another example of the invention;

FIG. 6 is a partial sectional view, similar to FIG. 4, showing a further example of practice of the invention;

FIG. 7 is a schematic diagram showing a refrigeration system wherein the example illustrated in FIG. 6 is organized as a three-phase refrigerator;

FIG. 8 is a schematic diagram indicating fluid piping and mechanical power transmission paths and means in one example of the refrigeration system according to the invention wherein pairs of variable compression and expansion spaces of a three-phase refrigerator as illustrated in FIG. 1 or 3 are used as a compressor for Joule-Thomson cycle;

FIG. 9 is a partial schematic diagram indicating a modification of the system illustrated in FIG. 7;

FIGS. 10(a) through 10(d) are schematic diagrams indicating movements of pistons for a description of the operational principle of a refrigerator based on the reverse Stirling cycle; and

FIG. 11 is a P-V diagram indicating the relationship between the pressure P and volume V of the working fluid in the above mentioned reverse Stirling cycle.

DETAILED DESCRIPTION As conducive to a full understanding of the nature and utility of this invention, the reverse Stirling cycle and the principle thereof will first be considered with reference to FIGS. 10 and 11.

When the compression piston P moves from the position (a) to the position (b) (position in FIG. (a) to the position in FIG. 10(b) the working fluid is compressed within the variable compression space V and the heat generated during this process is removed by a heat exchanger I-I, whereby the process is an isothermal compression. In the succeeding, process from (b) to (c), the above mentioned compression piston P and the expansion piston P move in the same direction, and the working fluid within the variable compression space V is transferred to the variable expansion space V During this second process, the working fluid passes through a regenerator R and is thereby cooled from a temperature T to T as indicated in FIG. 11. Consequently, the pressure decreases. In the succeeding process from (c) to (d), only the expansion piston P moves, and the working fluid expands within the variable expansion space V,; and absorbs heat from the surroundings thereby to undergo isothermal expansion to a point (d).

The expansion and compression pistons P and P then move in the direction opposite to that mentioned above, and the working fluid within the variable expansion space V, is heated by the regenerator R from T to T and is transferred to the variable compression space V undergoing a constant-volume process from (d) to (a) during which the pressure rises.

Referring to FIG. 1, -the' three-phase refrigerator shown therein has two crankshafts K, and K crankshaft K being coupled to and driven by a motor M mounted outside of the refrigerator casing and being coupled to the crankshaft K through mutually meshed identical gears G and G fixed respectively to the crankshafts K. and K Each of these crankshafts K, and K has three crankpins.

The three crankpins of the crankshaft K, are connected by connecting rods 8,, B and B respectively to compression pistons P P and P slidingly disposed in compression cylinders A A and A respectively. The three crankpins of the crankshaft K are connected by connecting rods B,,,, B and B respectively to expansion pistons P P g, and P slidingly disposed in expansion cylinders A A and A respectively. These six pistons are thus driven in sliding reciprocating motion as described more fully hereinafter.

A variable compression space V formed at the cylinder head between the compression cylinder A and the compression piston I is communicative, by way of a heat exchanger H a conduit pipe line T a regenerator R and a pipe line T,,,, with a variable expansion space V formed at the cylinder head between the expansion cylinder A and the expansion piston P Similarly, other variable compression spaces V and V respectively within the compression cylinders A, and A are respectively communicative, by way of heat exchangers H and H pipe lines T and T regenerators R and R and pipe line T and T with variable expansion spaces V and V The heads of the expansion cylinders A A and A there are provided with cold stations 0,, Q and Q for generating and recovering cold or refrigeration. The cold stations, 0,, Q and Q the regenerators R,, R and R and the expansion cylinders A A and A, are enclosed within a vacuum, thermally insulating case S.

Next, the operation of a three-phase refrigerator of the organization described above and as illustrated in FIG. 1 willl now be described with reference to FIGS. 2A, 2B, and 2C, which graphically represent by sine curves the variations in the volumes of the three variable expansion spaces and the three variable compression spaces, and in which the abscissa represents rotational angle of crank-shaft, the advance of time being in the rightward direction.

FIGS. 2A, 2B, and 2C respectively indicate the systems of the variable expansion spaces and the variable compression spaces of the three phases of the refrigerator. The part enclosed between the curves of each phase indicates the variation of volume of the working fluid sealed within the interior of that phase, and the cross-hatched portions of each phase indicate constantvolume processes. The abbreviation exp." deisgnates expansion; comp. compression; max. maximum value of each volume; and min." minimum value of each volume. The gap between min. and min. is a dead" volume.

The interval denoted by the angle 120 is the phase differencebetween the three expansion pistons and, similarly, is the phase difference between the three compression pistons.

It is apparent that the volume variation of the working fluid of this refrigerator is made up of the four variations or processes of compression, constant-volume variation, expansion, and constant-volume variation. The phase difference between the minimum value of the volume of the variable expansion space and the minimum value of the variable compression space is denoted by a. The variable expansion space V, is advanced by a relative to the variable compression space V This angle a is the angle from the state wherein the expansion piston P is at its higher position to the state wherein the compression piston P has successively thereafter arrived at its highest position as viewed in FIG. 1. This angle a is selected at a value of approximately degrees in FIG. 2.

Next, the mechanism of generation of cold or refrigeration will be described with respect to phase B of FIG. 2. compression starts from the position (i) of the variable compression space V Since the variable expansion space V at this time is varying in the direction of decreasing space volume, the working fluid, almost all of which is within the variable compression space V is subjected to a rapid rise in pressure.

When the compression reaches the point (ii), the variation of the volume of V changes to the increasing direction counter to that of V whereby the working fluid, which has been compressed within V begins to transfer into V That is, the working fluid undergoes a constant-volume change and transfers through the regenerator R into V At an angular position (iii) where the variable compression space V is at its minimum, and the compression piston P has reached its highest position. Almost all of the working fluid is within V Expansion starts from this point, and V is directed in its increasing direction. That is, the compression piston P starts to descend, while the expansion piston P also starts to descend, whereby the volume of V rapidly increases. Accordingly, expansion starts, and the working fluid undergoes adiabatic expansion to generate cold or refrigeration at the cold station Q When the operational point (iv) is reached, V g is directed in its decreasing direction, and,for this reason, the working fluid which has been cooled within V begins to move toward V Then, when the operation reaches the point (i), the one cycle is completed.

While one operational cycle has been described above withrespect to the B phase, exactly the same cycle iscarried out in each of the phases A and C with a phase difference therebetween of 120 degrees, and the entire operation is that of a three-phase refrigerator.

In a specific and practicalexample of the invention as illustrated in FIG. 3, the compression mechanism comprises, essentially, a crankshaft K, driven in rotation by a motor (not shown), a guide piston 71, a connecting rod B connecting the crankpin of the crankshaft K, and a wrist pin of the guide piston 71, a compression piston P and a piston rod 72 connecting the guide piston 71 to the compression piston P The compression piston P and the guide piston 71' are slidably disposed in vertical and coaxial cylinders formed on one lateral side (left side as viewed in F163) ofa cylinder block CB, and the crankshaft K, is horizontally and rotatably supported in a crankcase disposed below and contiguous to the cylinder blockCB. Thus, rotation of the crankshaft K, actuates the compression piston P in reciprocating motion to vary the volume of a compression space V between the head of the piston P and the head of its cylinder.

A gear G, fixedly supported on the crankshaft K, is meshed with a gear G having the same number of teeth and fixedly supported on a second crankshaft K parallel 'to the first crankshaft K,, whereby the crank shaft K is driven in rotation; This crankshaft K constitutes a member of an expansion mechanism having an organization similar to that of the above described compression mechanism and disposed on the opposite lateral side (right side as viewed in FIG. 3) of the cylinder block CB and crankcase. That is, the rotation of the crankshaft K is transmitted through a connecting rod B,,, a guide piston 73, and a piston rod 74 to an expansion piston P to cause this expansion piston to undergo reciprocating motion therebyto vary an expansion space V between the head of the piston P and the head of its cylinder.

Thus, it will be apparent that the phase difference a between the variable compression space V and the variable expansion space V, can be suitably selected by adjusting the angular mounting positions of the gears G, and G on their crankshafts K, and K Cooling water passages '75 are formed in the cylinder block CB around parts of the cylinders slidably accommodating the compression and expansion pistons P and P to conduct cooling water for removing heat generated in the variable compression space V, at the time of compression of the working fluid and, moreover, for cooling a heat exchanger I-I disposed in the cylinder block CB above the compression cylinder.

The guide pistons 71 and 73 are respectively provided with piston rings76, while the compression and expansion pistons P and P are respectively provided with gas-seal rings 77. Stuffing boxes 78 and 79 are provided in wall parts of the cylinder block CB between the compression cylinder and the guide cylinder of the guide piston 71 and between the expansion cylinder and the guide cylinder of the guide piston 73 and encompass the piston rods 72 and 74, respectively. Gasseal rings 80 are disposed coaxially above these stufi'mg boxes, andguide bushings 81 are disposed coaxially therebelow.

The stuffing boxes 78 and 79 are communicatively connected'to the'interior of the crankcase by a passage, in an intermediate part of which there is provided a gas purifier and pressure regulator 82, which operate to prevent contamination and transfer of the refrigerator working fluid between the variable compression and expansion spaces and to purify the same, at the same time regulating the pressures within the stuffing boxes and the crankcase.

In an intermediate part of a conduit pipe line communicatively connecting the variable compression and expansion spaces V and V there is provided a regenerator R for carrying out heat exchange accompanying transfer of the working fluid. This regenerator R is stuffed with metal netting or metal spheres. In the above mentioned conduit pipe line and in the vicinity of the outlet of the space V,, there is provided a buffer tank 84 with a pressure regulating valve 83 connected therebetween. This buffer tank 84 operates to regulate the pressure of the working fluid in accordance with the refrigeration temperature and the cooling capacity of the refrigerator. The diameters and strokes of the compression and expansion pistons are not necessarily the same and, similarly as in the problem of the determination of the difference a i n respective phases, are determined by factors such as the kind of working fluid, the charging pressure thereof, the'rotational speed of the crankshafts, the refrigeration' temperature, and the cooling capacity. Ordinarily, the diameter of the expansion piston is made smaller.

Another example of this invention as illustrated in FIG. 4 relates to a refrigerator of double-acting type. This refrigerator differs from that described above and illustrated by FIG. 3 in that volumes at two places, that is, variable compression spaces V and V are varied by means of a single compression piston P and, similarly, variable expansion spaces. V and V at two places are varied with a single expansion piston P In all other respects, the organization of this refrigerator is substantially the same as that of the preceding example illustrated in FIG. 3, and, therefore, repeated description thereof will be omitted.

The spaces V and V and the spaces V and V in combination, respectively, with regenerators R and R heat exchangers H and H,,, and cold stations Q and Q, constitute a two-phase refrigerator, and cold or refrigeration is produced at each of the cold stationsQ and Q While the temperature of the cold station Q becomes lower than that of the cold station in order to attain even lower temperature effect, the cold. or refrigeration produced at the cold station Q, is used to precool the regenerator R installed between the space V, and the space V In still another example of this invention as illustrated in FIG. 5, a regenerator R and a heat exchanger H are installed in an intermediate part of the pipe line connecting the variable spaces in the cylinders of an expansion piston P and a compression piston P which are driven in reciprocating motion with certain phase angles thereby to produce refrigeration at a cold station Q. These features are exactly the same as those of the preceding examples. In the instant example, however, there is provided a mechanism wherein the reciprocating motion of the compression piston P is further utilized to transfer cold or refrigeration to the outside of the refrigerator.

More specifically, an inlet valve 85 and an outlet valve 86 are provided in the head of the compression cylinder of the compression piston P thereby to form a pump chamber 87 for heat transfer. In addition, there are provided a cooler H, counterflow heat exchangers 88 and 89, a heat exchanger 90 to accomplish heat exchange with the cold station Q, a Joule-Thomson valve 91, and a cooling object 92.

The heat transfer mechanism of this invention operates in the following manner. During the descending stroke of the compression piston P the outlet valve 86 is closed, while the inlet valve 85 is open, whereby the refrigerating working fluid (refrigerant) is drawn into the pump chamber 87. During the ascending stroke of the compression piston P the states of valves are reversed, that is, the inlet valve 85 is closed, while the outlet valve 86 is opened, whereby the working fluid is discharged.

The fluid thus discharged is cooled by the cooler H and then, passing through the counterflow heat exchanger 88, the heat exchanger 90 for heat exchange with the cold station Q, and the counterflow heat exchanger 89 to undergo heat exchange, finally undergoing a Joule-Thomson expansion through the Joule- Thomson valve 91. As a result, cold at an even lower temperature is transfered to the outer part of the jacket S for vacuum insulation, whereby the cooling object 92 is cooled.

The working fluid which has accomplished its purpose of cooling the cooling object is caused by the piping on the return side to pass through the counterflow heat exchangers 89 and 88 in reverse direction to undergo heat exchange and, again passing through the inlet valve 85, is drawn into the pump chamber 87. Then, by repeating the above described process cycle, it is possible to cool the cooling object 92 in a continuous manner. Pumping means P may be additionally provided as indicated by single-dot chain line.

A further example of practice of this invention as illustrated in FIG. 6 differs from that described above and shown in FIG. in that the expansion piston and the regenerator are constructed integrally to form a combination RP In all other respects of organization and operation, this example is similar to that of FIG. 5, wherefore description thereof will not be repeated. Pumping means P may be additionally provided as indicated by single-dot chain line similarly as in the case illustrated in FIG. 6.

An example of a system wherein the example of FIGS. 5 and 6 is organized as a three-phase refrigerator is illustrated in FIG. 7. Since a description of the organization and operation of multi-phase refrigerators has already been given, it will not be repeated.

The dimensions of each of the expansion cylinders are determined in accordance with the required temperature, and in the case where a very low temperature is to be produced, the cylinder is made long. In the system illustrated in FIG. 7, the temperature of the cold station 0;, is lower than that of Q,. Helium which has been pressurized to a high pressure in a compressor 100 passes through a pipe line 101 to enter a counterflow heat exchanger 102, where it is cooled by cooled low-pressure helium 103 in the return line. The helium thus cooled is further cooled by the cold station Q, and enters a counterflow heat exchanger 104.

When this process is carried successively with counterflow heat exchangers 104, 105, and 106 and cold stations Q and Q the helium is cooled to a temperature below 6 K, and the refrigeration output is transferred outside of the refrigerator through a pipe line 107, the high-pressure helium being expanded by a Joule-Thomson valve 108. The helium thus liquefied and at a temperature of 4.2K then causes an object 109 to be cooled by a heat exchanger 110 and then, after passing through counterflow heat exchangers 106, 105, 104, and 102 and further through a blower or vacuum pump 111, returns to the compressor 21. In FIG. 7, reference numeral 112 designates agas holder, and reference character S, designates a thermally insulated vacuum case.

FIG. 8 illustrates one example of practice of the invention wherein pairs of the variable compression space V, and the variable expansion space V of the three-phase refrigerator shown in FIGS. 1 and 3 are used as a compressor for a Joule-Thomson cycle. The details of this circuit are as follows.

As indicated in FIG. 8, an electric motor M is coupled to a crankshaft K,, which is linked by connecting rods 3 and piston rods 5, pivotally connected by pins 4 to each other, to pistons P P and P to actuate these pistons in vertical reciprocating motion. The crankshaft K, and another crankshfat K are coupled by the meshing of gears G, and G of the same number of teeth fixed to the ends of these crankshafts similarly as in the preceding examples. The crankshaft K is linked by connecting rods 9, pins 10, and piston rods 11 to pistons P P and P, to actuate these pistons in vertical reciprocating motion.

The system within the enclosure of the dot-and dash chain line 12 in FIG. 8 is that of a Kirk cycle refrigerator based on the principle indicated in FIG. 1. The variable compression space V within the compression cylinder A is communicative with the variable expansion space V,., within the expansion cylinder A,, by way of a conduit pipe 13, a heat exchanger H,, a conduit pipe 14, a regenerator R,, and a conduit pipe 15. Similarly, the variable compression space V in the other compression cylinder A is communicative with the variable expansion space V in the expansion cylinder A, by way of a conduit pipe 16, a heat exchanger H a pipe 17, a regenerator R and a pipe 18.

The parts designated by reference characters 0, and 0 at the head ends of the variable expansion spaces V,,, and V, are cold stations for generating and recovering cold. The phase angles between the compression piston P and the expansion piston P,., and between the compression piston P and expansion piston P can be suitably selected by adjusting the enmeshment of the gears G and G fixed to the crankshafts K, and K2.

Furthermore, the system within the enclosure of the two-dots-and-dash chain line 21 in FIG. 8 is that of three-stage compressor for carrying out the Joule- Thomson cycle. The variable compression chamber V, within the first-stage compression cylinder A, is communicative by way of an outlet valve 22, a pipe 23, a heat exchanger 24, a pipe 25, and an inlet valve 26 with the variable compression chamber V within the second-stage and third-stage compression cylinder A The variable compression chamber V is communicative by way of an outlet valve 27, a pipe 28, a heat exchanger 29, a pipe 30, and an inlet valve 31 with a variable compression chamber V This variable compression chamber V is communicative by way of an outlet valve32, a pipe 33, a heat exchanger 34, and a pipe 35, and further through a counterflow heat exchanger 36, a heat exchanger 37 attached to the cold station 0,, a counterflow heat ex changer 38, a heat exchanger 39 for heat exchange with the cold station a counterflow heat exchanger 40, and a pipe 41 with a JouleThomson valve 42.

The working fluid which has produced an even lower temperature at the Joule-Thomson valve 42, is communicative with a variable compression chamber V, within the first-stage compression cylinder, A, byway of a cooling section 43, an ON-OFF valve 44, the counterflow heatexchangers 40, 3 8, and 36, apipe 45, and an inlet valve 46. A bypassvalve 47 is provided inthe pipe 41 to detect the temperature at the inlet of the Joule-Thomson valve 42, that is, the temperature of the pipe 41, and thereby to open or close the Joule- Thomson cycle bypass circuit.

The refrigeration producing part of the Kirk-cycle refrigerator and the counterflow heat exchangers of the Joule-Thomson circuit are enclosed and thermally isolated by a vacuum insulation case S for preventing infiltration of heat from the outside. v

The chambers V and V within the compression cylinders A and A apply back pressures respectively to compression pistons P and P and maintain their optimum'mechanical dynamic balance. At the same time, these chambers V and V are communicative with the outlet pipe 28 of the second-stage. compression chamber V, by way of pipes 49, 50 and 51 in order to prevent risingof lubricating oil for the bearing of the crankshaft K, and the pin 4. Similarly, the chambers V,,,, V and V within the cylinders A,, A and A are communicative with the'outlet pipe 23 of the firststage compression cylinder A, by way of pipes 52, 53, and 54. v

In addition, a buffer tank or gas holder 55 is communicative by way of a stop valve 56 with the pipe 45 and is connected by wayofa stop valve 57 to a highpressui'e gas tank (not shown), whereby the refrigation working fluid (refrigerant) can be supplied. Furthermore, a safety-valve 58 is provided for the purpose of releasing to the atmosphere the pressure of the gas holder 55 when it exceeds a predetermined pressure.

Another buffer tank 59 is communicative through a stop valve 60 with the pipe 35 and through a stop valve 61 with an outside vessel (not shown) and otherparts for supplying pressurized working fluid. Furthermore, pressure regulating valves 62 and 63 areprovided for maintaining the pressures within the pipes 14 and 17 respectively within predetermined pressure ranges and are respectively installed at intermediate points in pipes joining a stop valve 68- connected .to the above mentioned buffer tank 59 to the pipes 14 and 17.

The pipe 53 communicating with. the outlet pipe 23 of the first-stage compression chamber V,, the pipe 50 communicating with the outletpipe 28 of the secondstage compression chamber V and the outlet pipe v35 of the third-stage compression chamber V,, are commonly connected to-the low-pressure return circuit 45 of the Joule-Thomson cycle by way of safety valves 64, 66, and 65, respectively, adjusted to suitable operational pressures (set to the relief pressure). In addition,

a bypass valve 67 is installed between the pipes 35 and 45.

The refrigeration system of the above. described organization according to this invention operates inthe fol-. lowing manner. 1 v v In the Kirk-cycle refrigerator 12, the refrigerant (principally helium) compressed in the variable compression spaces V and V acquires heat of compression during the compression process,- which is removed in the heat exchangers 11, and 11 The refrigerant is further cooled to a lower temperature as it passes through the regenerators R, and Rgand expands in the variable expansionspaces V,., and V to produce refrigeration and thereby to cool the object to be cooled at the cold stations Q, and Q The refrigerant then passes through the regenerators and returns to the variable compression spaces V and V,,.

Next, the operation of the circuit of the Joule- Thomson cycle will be considered. In the three-stage compressor 21, the refrigerant- -(principally helium) compressed by the first-stage compression piston P, gives up its heat due to compression in the heat exchanger 24 and enters the second-stage compressor A Similarly, the refrigerant compressed 'inthe compression chamber V is cooled by the heat exchanger 29, and the refrigerant compressed to an even higher pressure in the third-stage compression chamber V is cooled by the heat exchanger 34, the refrigerant thus compressed and cooled being sent through the pipe 35. The compressed gas is then cooled further toa very low temperature by heat exchangers 36, 37,38, 39 and 40 reaches the Joule-Thomson valve 42, where it expands to produce an even lower temperatureand undergoes liquefaction. i

The refrigerant which has been cooled to this low temperature absorbs heat in the heat exchanger '43 for heat exchange with the outside. Then, passing through the counterflow heat exchangers 40, 38, and 36 to cool successively the above mentioned refrigerant at high pressure, the refrigerant which has thus absorbed heat enters the variable compression space V, through the inletvalveof the first-stagecompression cylinder A,,

In the event that the discharge pressure of any one of the first,'second, and third stages rises to' an abnormally high pressure because of some unexpected circumstance,'the pertinent safetyvalve among the safety valves 64,65, and 66 set at appropriate relief pressures operates to releaselthe refrigerant to the low-pressure circuit 35 on the return side. 7 I r 'I r Therefrigerant can be supplied to the Kirk cycle refrigerator 1 2 from the pipe 35 by opening the stop valves and 68'. [US also possible to supplythe refrigerant to, the Kirk cycle refrigerator 12 by closing the stop valve 60 supplying the refrigerant through the valve 61 from an outside high-pressure gastank (not shown) independently of the compressor 21 for the Joule-Thomson cycle.

The bypass valve 47 of the capable of operating to detect the temperature .between the heat exchanger 40 and the valve 42 and, depending onthe value of this temperature, in relation to its set temperature, to bypass the refrigerant. In gen eral, when the refrigerant temperature becomes lower Joule-Thomson cycle is lower temperature can be attained together with liquefaction of the gaseous refrigerant.

In a modification, as illustrated in FIG. 9, of the preceding example, a precooling circuit is additionally inserted between the third-stage compression chamber V and the counterflow heat exchanger 36. In the precooling circuit of this circuit, a refrigerator 69 having a structure separated from the main system and having an excellent efficiency at a relatively high temperature is used, and, by means of heat exchangers 70 and 71, precooling of a Joule-Thomson cycle working fluid can be carried out thereby to improve the efficiency of the main operational cycle.

By the practice of this invention as described above, use is made of a so-called Kirk cycle refrigerator comprising a compression section, an expansion section, heat exchangers, and regenerators, in which compression pistons and expansion pistons are connected to re spectively separated crankshafts intercoupled by gears, which can be so intermeshed as to set a phase angle between the two kinds of pistons thereby to obtain maximum refrigeration output with respect to the objective temperature. Furthermore, the work of the refrigeration working fluid (refrigerant) during its refrigeration operation can also be recovered by the expansion piston and returned to the side of the motive power means, and maximum thermal and mechanical efficiency can be attained.

By using a Kirk cycle refrigerator as described above for the precooling circuit of the Joule-Thomson cycle; organizing the first-stage or multistage compressor for the above mentioned Joule-Thomson cycle and a suit able number of Kirk cycle refrigerators, moreover, as a unitary apparatus; supplying the refrigeration working fluid compressed to a high pressure by the above mentioned compressor for the Joule-Thomson cycle as the working fluid of the Kirk cycle refrigerators; applying a back pressure on the reciprocating pistons; maintaining the optimum mechanical dynamic balance; and, in addition, causing the above mentioned back pressure to be higher than the pressure within the crankcase, it is possible to prevent the infiltration of the lubricating into the working fluid.

As will be apparent from the foregoing description, this invention provides a refrigeration system affording the following features which are not attainable by conventional refrigerators. The system of the invention employs a plurality of cylinders, and the phase angles can be easily and suitable selected so as to produce the maximum refrigeration output (or cooling capacity). In addition, the compressors and refrigerators are integrally organized. These features, in combination, afford the attainment of a very high thermal efficiency, silent refrigerators producing very little mechanical vibration and noise, and long serviceable life of the mechanical parts.

In addition, there is little or no contamination of the refrigeration working fluid, whereby maintenance is facilitated. Furthermore, reductions in the size, weight, number of parts, and price of the system become possible, and the operational reliability is increased.

I claim:

I. A refrigeration device comprising:

a main body;

at least one refrigerant expansion cylinder formed in said main body;

at least one refrigerant compression cylinder also formed in said main body and isolated from said expansion cylinder;

an expansion piston slidably disposed in said expansion cylinder and cooperating therewith to define a refrigerant expansion space;

a compression piston slidably disposed in said compression cylinder and cooperating therewith to define a refrigerant compression space;

means communicatively connecting said expansion space and said compression space;

a heat exchanger in said connecting means near said compression space;

a cold station in said connecting means adjacent said expansion space;

. a regenerator in said connecting means between said heat exchanger and said cold station;

a pair of crankshafts connected to drive said expansion piston and said compression piston, respectively, in reciprocating motion;

a prime mover drivingly connected to one of said crankshafts; and

means mechanically interconnecting said crankshafts for effecting synchronous rotation thereof with a specific phase angle difference therebetween, whereby cyclic compression and expansion of refrigerant are effected in said compression and expansion spaces, respectively, and cyclic flow of the refrigerant occurs in said connecting means so that refrigeration is produced.

2. The refrigeration device of claim 1 further including means forming a second expansion space and a sec- 0nd compression space in said expansion and compression cylinders on opposite sides of said first expansion and compression spaces, respectively, second means for communicatively connecting said second expansion space to said second compression space, and a second heat exchanger, a second regenerator and a second cold station provided in said second connecting means.

3. The refrigeration device of claim 1 wherein said interconnecting means is a pair of meshing gears mounted on said crankshafts, respectively.

4. The refrigeration device of claim 3 wherein said one of said crankshafts connected with the prime mover is the crankshaft for said compression piston.

- 5. The refrigeration device in claim 1 further including means for preventing contamination'and transfer of the refrigerant, provided between the expansion and compression cylinders and spaces enclosing the crankshafts.

6. The refrigeration device of claim 1, further including a Joule-Thomson refrigerating system operatively associated with and cooled by said cooling station.

7. The refrigeration device of claim 6, wherein said Joule-Thomson refrigerating system includes a refrigerant compressor and counter-flow heat exchangers whereby the resulting refrigeration effect is transferred to a remote position. i

8. The refrigeration device of claim 7, wherein said compression piston and cylinder cooperate to form said refrigerant compressor for the Joule-Thomson system, said compressor including inlet and outlet valves formed in the wall of the compression cylinder.

9. The refrigeration device of claim 7, further including a refrigerant pumping means provided in the circuit of the Joule-Thomson refrigerating system.

cluding means to selectively connect the Joule- Thomson system to said connecting means between the first expansion and compression spaces, thereby to supply the refrigerant from the Joule-Thomson system to the main refrigeration system.

13. The refrigeration device of claim 12, further including two-way pressure regulating valves provided in said selectively connecting means. 

1. A refrigeration device comprising: a main body; at least one refrigerant expansion cylinder formed in said main body; at least one refrigerant compression cylinder also formed in said main body and isolated from said expansion cylinder; an expansion piston slidably disposed in said expansion cylinder and cooperating therewith to define a refrigerant expansion space; a compression piston slidably disposed in said compression cylinder and cooperating therewith to define a refrigerant compression space; means communicatively connecting said expansion space and said compression space; a heat exchanger in said connecting means near said compression space; a cold station in said connecting means adjacent said expansion space; a regenerator in said connecting means between said heat exchanger and said cold station; a pair of crankshafts connected to drive said expansion piston and said compression piston, respectively, in reciprocating motion; a prime mover drivingly connected to one of said crankshafts; and means mechanically interconnecting said crankshafts for effecting synchronous rotation thereof with a specific phase angle difference therebetween, whereby cyclic compression and expansion of refrigerant are effected in said compression and expansion spaces, respectively, and cyclic flow of the refrigerant occurs in said connecting means so that refrigeration is produced.
 2. The refrigeration device of claim 1 further including means forming a second expansion space and a second compression space in said expansion and compression cylinders on opposite sides of said first expansion and compression spaces, respectively, second means for communicatively connecting said second expansion space to said second compression space, and a second heat exchanger, a second regenerator and a second cold station provided in said second connecting means.
 3. The refrigeration device of claim 1 wherein said interconnecting means is a pair of meshing gears mounted on said crankshafts, respectively.
 4. The refrigeration device of claim 3 wherein said one of said crankshafts connected with the prime mover is the crankshaft for said compression piston.
 5. The refrigeration device in claim 1 further including means for preventing contamination and transfer of the refrigerant, provided between the expansion and compression cylinders and spaces enclosing the crankshafts.
 6. The refrigeration device of claim 1, further including a Joule-Thomson refrigerating system operatively associated with and cooled by said cooling station.
 7. The refrigeration device of claim 6, wherein said Joule-Thomson refrigerating system includes a refrigerant compressor and counter-flow heat exchangers whereby the resulting refrigeration effect is transferred to a remote position.
 8. The refrigeration device of claim 7, wherein said compression piston and cylinder cooperate to form said refrigerant compressor for the Joule-Thomson system, said compressor including inlet and outlet valves formed in the wall of the compression cylinder.
 9. The refrigeration device of claim 7, further including a refrigerant pumping means provided in the circuit of the Joule-Thomson refrigerating system.
 10. The refrigeration device of claim 1, wherein said regenerator is formed integral with said expansion piston.
 11. The refrigeration device of claim 7, wherein said refrigerant compressor for the Joule-Thomson refrigerating system is operatively so connected to said crankshafts for the expansion and compression pistons as to constitute a balancer for the pistons.
 12. The refrigeration device of claim 7, further including means to selectively connect the Joule-Thomson system to said connecting means between the first expansion and compression spaces, thereby to supply the refrigerant from the Joule-Thomson system to the main refrigeration system.
 13. The refrigeration device of claim 12, further including two-way pressure regulating valves provided in said selectively connecting means. 